Magnum floor heater: make dp 2 optional

Issue #3268

custom_components/tuya_local/devices/mrc_magnum_floorheater.yaml

@@ -10,12 +10,14 @@ entities:
       - id: 2
         type: string
         name: hvac_mode
+        optional: true
         mapping:
           - dps_val: AUTO
             value: auto
           - dps_val: MANUAL
             value: heat
           - value: heat
+            hidden: true
       - id: 2
         type: string
         name: preset_mode